Shared memory: mapping shared arenas into different client with the same in-process address

[sighingnow]

Describe your problem

It would be great if pointers keep valid between processes, that means a data structure on vineyard can be directly used by another process, without the builder & resolver process, and may help to reduce current requirements for code generation.

Additional context

See also: https://man7.org/linux/man-pages/man2/mmap.2.html

[sighingnow]

See also: #301.